In-line explosion arrester

ABSTRACT

This invention relates to a system for detecting an explosion in a pipeline carrying molten explosive material and halting the spread thereof by blocking the propagation of the detonating wave by a detonation arresting means that is electrically activated by an electronic switch which is sensitive to the initial detonation.

ilnite States Patent 1 Jalblansky 1 lN-LINE EXPLOSION ARRESTER [75]Inventor: Louis Jablansky, Fair Lawn, NY.

[73] Assignee: The United States of America as represented by theSecretary of the Army, Washington, DC

[22] Filed: May 3, 1971 [21] App]. No.: 139,337

[52] US. Cl 137/68, 251/63, 317/18 R,

317/33 SC, 317/151 [51] Int. Cl. Fl6k 3/00, Fl6k 17/36 [58} Field ofSearch ..l37/67-71; 3l7/DIG. 8

[56] References Cited UNITED STATES PATENTS 1,284,197 11/1918 Larner eta1. 137/68 ELECTRONI C SWITCH June 19, 1973 2,399,843 5/1946 Adams137/67 X 3,022,793 2/1962 3,332,432 7/1967 3,509,942 5/1970 Lindberg137/67 X Primary ExaminerMartin P. Schwadron Assistant Examiner-RichardGerard Attorney-Harry M. Saragovitz, Edward J. Kelly, Herbert Berl andErnest F. Weinberger [57] ABSTRACT This invention relates to a systemfor detecting an explosion in a pipeline carrying molten explosivematerial and halting the spread thereof by blocking the propagation ofthe detonating wave by a detonation arresting means that is electricallyactivated by an electronic switch which is sensitive to the initialdetonation.

4 Claims, 9 Drawing Figures V lN-LINE EX PLOSION ARRESTE R Patented June.19 1973 3,739,796

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Patented June 19, 1973 'r Shets-Sheet v INVENTOR) LOUIS JABLANSKY @www mIN-LINE EXPLOSION ARRESTER The invention described herein may bemanufactured, used and licensed by or for the Government forgovernmental purposes without the payment to me of any royalty thereon.

BACKGROUND OF THE INVENTION This invention relates to a system forarresting detonations in a continuous process explosive pipe-line suchas those used in the manufacture of molten TNT and similar explosivematerials.

Prior art devices using explosive arresters were not capable of stoppinga detonation from propagating in a conduit containing molten explosivesuch as tri-nitrotoluene. Devices used in the past, have attempted toarrest the propagation of an initial explosion in a line carrying theexplosive by controlling and limiting the diameter of the pipe and/or bythe insertion of loops in the production line. Both of these methodshave been found to be of limited merit. In manufacturing operations,where molten explosive is being transported from one processingoperation to another, limiting the conduit to a critical diameter whichwill inhibit the propagation will not permit adequate volume of materialto flow; likewise where loops of sufficient number are in troduced intothe line to substantially inhibit propagation of a detonation theirresultant effect in restricting the volume of flow through the conduithas proved objectionable.

SUMMARY OF THE INVENTION The present invention is a system forinterrupting the propagation of a detonation wave in a conduit carryingexplosive material such-as molten tri-nitro-toluene by attenuating theaforesaid wave to a minimum energy level, either upstream and/ordownstream from the explosion point, thereby rendering the initialexplosion ineffective in initiating and propagating further explosionsalong the line.

One of the objects of this invention is to provide quenching action inan explosive train in approximately one millisecond.

Another object of this invention is to provide an arresting device forquenching pipeline explosions which is suitable for more than one typeof explosive.

Another object of this invention is to provide a system for interruptingthe propagation of a detonation wave in a conduit containing amoltenexplosive which system does not restrict the normal material flowthrough the conduit.

Another object of this invention is to provide a means for interruptingthe detonation wave in an explosive carrying pipeline withoutsubstantially limiting the physical size or shape of the line.

Another object of this invention is to provide a simple, cheap andcompact means for effectively quenching an accidental explosion in anexplosive carrying pipeline.

For a better understanding of the present invention, together with otherand further objects thereof, reference is made to the followingdescription taken in connection with the accompanying drawings.

. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic and blockdiagram of an in-line explosion arrester, which closes a passageway whenactivated by an electronic sensing circuit and switch.

FIG. 6 is a sectional view of aforementioned in-line explosion arresterillustrated in FIG. 4, and taken along line 6-6.

FIG. 7 is a cross-sectional expanded, elevational, view of one of thetwo detonation arresting means schematically illustrated in FIG. 2.

FIG. 8 is a partial sectional and plan view of the detonation arrestingmeans of FIG. 7 taken along line 88.

FIG. 9 is a cross section of the detonation arresting means taken alongline 9-9 of FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIGS. 1 and 2,a detonation sensor breakwire 10 is coiled about the longitudinalcircumference of the liquid explosive pipeline 12 having a product flow14. The detonation breakwire sensor 10 is electrically connected to apair of input terminals 18 and 20 of an electronic switch circuit 16.Circuit 16 maintains an in-line explosion arresting means 26 in FIG. 1and an alternative arresting means 28, 28 in FIG. 2 non-operative solong as the breakwire sensor is intact. When an explosion causes thebreakwire 10 to rupture anywhere along pipe-line 12 or 12, theelectronic switch circuit 16 will energize the detonation arrestingmeans 26 and 28 through detonator leads 23 and 25 and to arresting means28' through a parallel connection at junctions 27 and 29. In thearrangement shown in FIG. 1 the in-line explosion arresting means 26prevents the propagation of the explosive train by blocking the line. Abarrier attenuates the detonation wave to a minimum energy levelrendering the wave incapable of further explosive propagation. In FIG. 2the explosion arresting means 28 and 28' cause the explosive sectionalpipe-line 12' to separate from line 12 thereby opening up the explosivepipe-line 12 causing a critical discontinuity in the explosive fluid andthereby preventing propagation of the explosion. In both arrangementsdescribed above the arresting means will interrupt the propagation ofthe detonating wave in approximately one millisecond after rupture ofthe breakwire sensor.

FIG. 3 is an electrical schematic of the electronic switch 16illustrated in FIGS. 1 and 2. A power source 17 is connected through aswitch 19 and charging resistor 30 across the series combination siliconcontrolled rectifier 34 and electric detonator 52, also shown on FIGS. 4and 7. Electric detonator leads 23 and 25 are connected to the switch 16output terminals 22 and 24. A capacitor 35 is connected in parallel withthe series combination of the silicon controlled rectifier and electricdetonator 52 at junctions 42 and 21. A voltage dividing resistor 32 isconnected at one end to the common junction 42 between the limitingresistor 30, an anode lead 36 and capacitor 35, and the other end to thecommon junction 46 between the trigger electrode 40 and the electricalconnection 47. The other end of the electrical connection 47 isconnected to terminal 18. Junction 21 is also connected to terminal 20.The low resistance path of the breakwire sensor when connected toterminals 18 and 20 keeps the trigger electrode of silicon controlledrectifier 34 at a low potential and therefore in a cut-offnon-conducting condition. When the breakwire sensor 10 is broken thepotential at junction 46 is raised to a voltage approaching anodepotential causing the silicon controlled rectifier 34 to conduct therebydischarging the energy stored in capacitor 35 to the electric detonator52, and initiating the detonation arresting means 26, 28 and 28.

FIG. 4 shows the details of an in-line explosion arrester 26 illustratedin FIG. 1. A threaded detonator holder and closure 48 has an axial bore51 which is filled with an insulating cement which holds detonator leads23 and 25. A smaller axial bore 53 permits the passage of leads 23 and25 to a larger axial bore 55 which contains an electrical detonator 52.The detonator holder 48 is coaxially threaded into a bushing 54 which isin turn threaded into one end of the detonation trap housing 60. A space56 is provided between the threaded portion 49 of the detonator holder48 and an inner bore 57 of the threaded bushing 54. This inner space 56permits gases generated by the detonator 52 to expand, therebyminimizing any shock wave generated by detonator 52. A hollow steelcylindrical plug 68 is operatively positioned below the threaded bushing54 and slidably engages the inner wall of the longitudinal bore 61 ofhousing at one end of its outer peripheral surface. Steel plug 68 atsaid first end has a first annular O-ring groove which contains a firstO-ring 64 and a transverse bore on one side of said first end forholding a shear pin 62. The shear pin 62 fits in a shear pin housinggroove 63 permitting the bottom surface 67 of the threaded bushing 54 tomate with the bottom surface of the threaded housing bore 69. Steel plug68 has a first threaded bore 59 on an open end and a second smalleraxially aligned bore 81 on a closed end. A steel threaded insert 70 isthreaded onto the first threaded steel plug bore 59 closing the secondplug bore 81 and retaining therein a low density polyurethane foam 72.The steel threaded insert 70 has a central axially aligned bore 79 andinserted therein is a compressible wafer 58 oppositely disposed and inline with the electric detonator 52. The purpose of the compressiblewafer 58 is to absorb some of the shock caused by detonator 52. Thepurpose of the polyurethane foam 72 is to further attenuate thedetonation wave and to prevent spalling of wall of plug bore 81. TheTEFLON sleeve transverse port member 66 retains the other smaller closedend of steel plug 68 in a cup shaped recess 66' therein in housing 60and lines up the transverse bore 71 with transverse bores of the 60'housing 60. A second annular O-ring groove 65' is located in the bottomperipheral surface of the TEF- LON sleeve 66 transverse to thelongitudinal axis 86 on one wall of the transverse bore 71; a secondO-ring 64' is located in the aforesaid second O-ring groove 65'. O ring64' acts as a seal to prevent the molten explosive product from enteringinto the space between housing 60 and TEFLON sleeve 66. A third annularO-ring groove 65" is located transverse to the longitudinal axis 86 onthe other wall of transverse bore 71 and has therewithin a third O-ring64" which acts as a seal to retain the molten explosive material withinthe transverse bore 71 and the housing 60. An aluminum decelerating stop76 which is circular in cross section when viewed along line 6-6 isattached to the underneath side of the transverse bore wall 71' byscrews 84 and is slightly smaller in diameter than the inside diameterof the longitudinal central bore wall 61 of housing 60. Pipe flanges 74and 74 are circumferentially welded at 73, 73' to housing 60 so that theflange bores 75, 75 are axially aligned with the transverse bore 60'.Fourth annular O-ring grooves 65 and fourth 0" rings 64" are located inthe flange mating faces 77, 77 to form a seal with mating flanges (notshown) which are hermetically attached to pipe line 12 so that theexplosive molten material may be maintained therein. Housing 60 has athreaded boss 83 on its other end and to which a threaded tapered stop82 is screwed thereon. The wall of tapered bore 80, located adjacent toclearance space 78, gradually slows decelerating stop 76 which has beengiven motion by electrical detonator 52, effecting a closure oftransverse bore 60' with a minimum of shock impact thereby safelyattenuating the approaching detonating wave along pipe-line 12.

An initiating pulse from the electronic switch 16 through leads 23 and25 will activate electric detonator 52 causing gases to be generatedabove wafer 58; the pressure of these gases creates a force againststeel plug 68 causing shear pin 62 to shear and the TEFLON sleeve 66 tomove in a direction in line with longitudinal axis 86 closing thetransverse bore 60 and thereby attenuating any subsequent detonationwave from being propagated along explosive line 12.

In FIG. 5, a cross-sectional view taken along line 55 of FIG. 4, we seethe concentric arrangement of polyurethane foam 72, the retaining wallsof steel plug 68 surrounding the foam 72, and the TEFLON sleeve wall 66intermediate to the steel plug 68 and the surrounding housing 60.

FIG. 6 shows a cross-sectional view of the housing 60 and thedecelerating stop 76 when the detonation arresting means 26 is in itsopen state. Housing 60 is circumambient the decelerating stop 76 andseparated therefrom by clearance space 85. A plurality of screws 84, 84'holds the decelerating stop 76 affixed to the transverse bore wall 71'(not shown).

FIG. 7 shows, in partial cross-section, one of two identical detonationarresting means 28 and 28' which upon receipt of an initiating signalfrom electronic switch 16 will cause the sectional pipeline 12 in FIG. 2to separate from pipe line 12. Upper flange 90 has an axial firstcentral bore 104 on its outer surface 91 and concentric therewith asecond central bore 106; pipeline 12 is positioned in the upper flangefirst bore 104 and welded to the outer surface 91 at weld 99. In asimilar manner lower flange 92 has an outer surface 93 welded tosectional pipeline 12' at weld 99. Sectional pipeline 12' is axiallyaligned with pipeline 12 by the lower flange first central bore 112 anda concentric second central bore of smaller diameter 108. The upperflange 90 is connected to the lower flange 92 by a plurality of bolts102, 102', 102" and 102" (see FIGS. 8 and 9) which pass through upperflange clearance holes 105, 105, 105" and 105" into aligned holes 103,103', 103" and 103". A circular upper fuze ribbon channel is positionedimmediately adjacent to electric detonator hole 109 which holds theelectric detonator 52. A matching circular lower fuze ribbon channel 97is positioned opposite to the upper fuze ribbon channel 95 so that whenboth flanges are assembled together a closed annular channel is formedfor containing the detonating fuze ribbon 94 therein. A circularlyshaped upper flange tongue 98, of smaller diameter than the fuze ribbonchannels 95 and 97, mates with an annular channel 96 located in thelower flange 92. An annular O-ring channel 101 of smaller diameter thanthe upper flange tongue 98 is intermediate to a central bore 104 and theupper flange tongue 98 and located in the same flange face as the upperfuze ribbon channel 95. An O-ring 100 is positioned within the O- ringchannel 101 and space formed between channel 101 and lowerflange innersurface 111. The O-ring 100 in contact with the inner surface 111 of thelower flange 92 acts as an effective seal preventing the moltenexplosive in pipe line 12 and sectional pipe line 12 from escaping orfrom contacting detonating fuze ribbon 94 or the electrical detonator52. A threaded hole 110 is opposite to and connected with electricdetonator hole 109 thereby permitting detonator holder 48 and electricdetonator 52 to be operatively positioned immediately adjacent to thedetonating fuze ribbon 94.

FIG. 8 shows a plan and partial cross-section taken along line 88 ofFIG. 7 of the upper flange outer surface 91 with a plurality of screws102, 102, 102", 102" positioned between pipeline l2 and the outsidediameter of the upper flange 90.

FIG. 9 shows a view of the upper flange inner surface taken along line9-9, a cross-section of detonating fuze ribbon 94, electric detonator52, detonator holder 48, and a plurality of screws 102, 102, 102 and102" in clearance holes 105, 105, 105" and 105" respectively. This viewshows the concentric positions of the O-ring 100, O-ring groove 101 andthe detonating fuze ribbon 94 about the second central bore 106.Detonator holder closure 48 and electric detonator hole 109 are axiallyin line and radially positioned with respect to detonating ribbon 94 sothat the electric detonator 52, located in electric detonator hole 109,is adjacent to detonating ribbon 94.

An initiating pulse from the electronic switch 16 through leads 23 and25 and 23' and 25' in parallel connection at junctions 27 and 29, asshown in FIG. 2, will cause the electric detonator 52, as shown in FIG.9, in detonation arresting means 28 and 28' respectively to tire thedetonating fuze ribbon 94. The mild explosive force of detonatingribbons 94 and 94' (not shown) in arresting means 28' will cause thelower flange halves 92 and 92' (not shown) of detonating arresting means28 and 28' to simultaneously separate from the upper flange 90 and 90(not shown causing line 12' to be opened, thereby preventing thepropagation of the detonation wave along pipeline 12.

From the above description it will be evident that the inventionprovides a system for rapidly detecting an explosion in an explosivematerial carrying pipe-line and arresting the detonation wave therebypreventing further propagation of the explosion.

I wish it to be understood that I do not desire to be limited to theexact detail of construction shown and described for obviousmodification will occur to a person skilled in the art.

What is claimed is:

l. A system for detecting an initial explosion in a pipeline carryingexplosive materials and arresting said explosion prior to thepropagation of a detonation wave along said pipeline which comprises:

a breakwire sensor operatively positioned around said pipeline;

an electronic switch having a pair of input terminals electricallyconnected to said breakwire for maintaining said electronic switchnon-operative when said breakwire is intact, and a pair of outputterminals for supplying a voltage pulse when said breakwire is broken,and which includes;

a power source;

a silicon controlled rectifier having an anode terminal connected to apositive terminal of said power source through a series connectedcharging resistor and switch, a trigger electrode connected to thecommon junction of a first terminal of said pair of input terminals andto one end of a voltage dividing resistor, said voltage dividingresistor having its other end connected to the common junction of saidcharging resistor and said anode terminal, a cathode terminal connectedto a first terminal of said pair of output terminals;

a load capacitor having one terminal connected to the common junction ofa second terminal of said pair of input terminals and a second terminalof said output pair of terminals and the negative side of said powersource, and a second terminal connected to the common junction of saidanode terminal, said voltage dividing resistor, and said chargingresistor, whereby said capacitor discharges its stored energy to saidpair of output terminals when said breakwire sensor is broken, causingsaid silicon rectifier trigger electrode to be more positively biased,triggering said silicon rectifier; and

means for arresting a detonation disposed proximate said pipelineelectrically coupled to saidpair of output terminals and responsive tosaid voltage pulse.

2. A system for detecting an initial explosion in a pipeline carryingexplosive materials and arresting said explosion prior to thepropagation of a detonation wav'e along said pipeline which comprises:

a breakwire sensor operatively positioned around said pipeline;

an electronic switch having a pair of input terminals electricallyconnected to said breakwire for maintaining said electronic switchnon-operative when said breakwire is intact, and a pair of outputterminals for supplying a voltage pulse when said breakwire is broken;and

means for arresting a detonation disposed proximate said pipelineelectrically coupled to said pair of output terminals and responsive tosaid voltage pulse, and which includes;

a housing having a longitudinal bore internally threaded on one end, athreaded boss on a secend end, and an interconnecting transverse boreperpendicular to said longitudinal bore;

means for connecting said explosive pipeline to said transverse bore;

an electrical detonator;

means for holding said electrical detonator oppositely positioned andaxially aligned to said longitudinal bore cited in claim 2 wherein saidmeans for blocking comprises:

a low friction transverse port sleeve member, slidably positioned withinsaid longitudinal bore, having a cup shaped recess on a first end and atransverse bore wall on a second end concentric with said housingtransverse bore thereby permitting said explosive materials to passtherethrough when said port member is in an open position, and blockingsaid pipeline when said port member is in a closed position;

a steel hollow plug located in said cup recess having a first threadedbore on a first open end and a second smaller axially aligned bore on aclosed end;

a steel threaded insert having a recess therein and threaded into saidfirst threaded bore of said steel hollow plug seals said second axiallyaligned bore of said steel plug;

a polyurethane foam within said second axially aligned bore of saidsteel plug further attenuates the detonation wave;

a compressible wafer located in said steel threaded insert recess andoppositely disposed from said electrical detonator absorbs shock fromsaid electrical detonator;

means for sealing said sleeve-transverse member from said transversebore so that said explosive material remains in said pipeline;

means for sealing said steel plug to said longitudinal housing bore sothat gases from said electrical detonator will not escape in theintervening space therethrough; and

means for retaining said steel plug and said transverse port sleevemember in an open position so that said transverse housing bore is opento pass explosive material when said electrical detonator has notbeen'activated by an output pulse from said electronic switch outputterminals.

4. A detonator detecting and arresting system as recited in claim 2wherein said means for decelerating comprises:

a tapered stop having a partially threaded first section internal borescrewed upon said housing threaded boss with its axis concentric withsaid longitudinal bore, a second tapered section having a first internaldiameter equal in size to the diameter of said longitudinal bore and asecond section smaller diameter; and

a decelerating cylindrical stop having an outside diameter smaller thanthe inside diameter of said longitudinal bore and larger in diameterthan said second tapered section diameter of said tapered stop, saidstop is attached to the underneath side of said blocking mean,, therebypermitting closure of said transverse bore with a minimum of shockimpact.

1. A system for detecting an initial explosion in a pipeline carryingexplosive materials and arresting said explosion prior to thepropagation of a detonation wave along said pipeline which comprises: abreakwire sensor operatively positioned around said pipeline; anelectronic switch having a pair of input terminals electricallyconnected to said breakwire for maintaining said electronic switchnon-operative when said breakwire is intact, and a pair of outputterminals for supplying a voltage pulse when said breakwire is broken,and which includes; a power source; a silicon controlled rectifierhaving an anode terminal connected to a positive terminal of said powersource through a series connected charging resistor and switch, atrigger electrode connected to the common junction of a first terminalof said pair of input terminals and to one end of a voltage dividingresistor, said voltage dividing resistor having its other end connectedto the common junction of said charging resistor and said anodeterminal, a cathode terminal connected to a first terminal of said pairof output terminals; a load capacitor having one terminal connected tothe common junction of a second terminal of said pair of input terminalsand a second terminal of said output pair of terminals and the negativeside of said power source, and a second terminal connected to the commonjunction of said anode terminal, said voltage dividing resistor, andsaid charging resistor, whereby said capacitor discharges its storedenergy to said pair of output terminals when said breakwire sensor isbroken, causing said silicon rectifier trigger electrode to be morepositively biased, triggering said silicon rectifier; and means forarresting a detonation disposed proximate said pipeline electricallycoupled to said pair of output terminals and responsive to said voltagepulse.
 2. A system for detecting an initial explosion in a pipelinecarrying explosive materials and arresting said explosion prior to thepropagation of a detonation wave along said pipeline which comprises: abreakwire sensor operatively positioned around said pipeline; anelectronic switch having a pair of input terminals electricallyconnected to said breakwire for maintaining said electronic switchnon-operative when said breakwire is intact, and a pair of outputterminals for supplying a voltage pulse when said breakwire is broken;and means for arresting a detonation disposed proximate said pipelineelectrically coupled to said pair of output terminals and responsive tosaid voltage pulse, and which includes; a housing having a longitudinalbore internally threaded on one end, a threaded boss on a second end,and an interconnecting transverse bore perpendicular to saidlongitudinal bore; means for connecting said explosive pipeline to saidtransverse bore; an electrical detonator; means for holding saidelectrical detonator oppositely positioned and axially aligned to saidlongitudinal bore; means for blocking said transverse bore slidablypositioned in said longitudinal bore and operatively responsive to saidelectrical detonator; and means for decelerating said means forblocking, thereby permitting the closure of said transverse bore andsaid attached pipeline with a minimum of shock impact while attenuatingthe detonating wave in said pipeline.
 3. A detonator detecting andarresting system as recited in claim 2 wherein said means for blockingcomprises: a low friction transverse port sleeve member, slidablypositioned within said longitudinal bore, having a cup shaped recess ona first end and a transverse bore wall on a second end concentric withsaid housing transverse bore thereby permitting said explosive materialsto pass therethrough when said port member is in an open position, andblocking said pipeline when said port member is in a closed position; asteel hollow plug located in said cup recess having a first threadedbore on a first open end and a second smaller axially aligned bore on aclosed end; a steel threaded insert having a recess therein and threadedinto said first threaded bore of said steel hollow plug seals saidsecond axially aligned bore of said steel plug; a polyurethane foamwithin said second axially aligned bore of said steel plug furtherattenuates the detonation wave; a compressible wafer located in saidsteel threaded insert recess and oppositely disposed from saidelectrical detonator absorbs shock from said electrical detonator; meansfor sealing said sleeve-transverse member from said transverse bore sothat said explosive material remains in said pipeline; means for sealingsaid steel plug to said longitudinal housing bore so that gases fromsaid electrical detonator will not escape in the intervening spacetherethrough; and means for retaining said steel plug and saidtransverse port sleeve member in an open position so that saidtransverse housing bore is open to pass explosive material when saidelectrical detonator has not been activated by an output pulse from saidelectronic switch output terminals.
 4. A detonator detecting andarresting system as recited in claim 2 wherein said means fordecelerating comprises: a tapered stop having a partially threaded firstsection internal bore screwed upon said housing threaded boss with itsaxis concentric with said longitudinal bore, a second tapered sectionhaving a first internal diameter equal in size to the diameter of saidlongitudinal bore and a second section smaller diameter; and adecelerating cylindrical stop having an outside diameter smaller thanthe inside diameter of said longitudinal bore and larger in diamEterthan said second tapered section diameter of said tapered stop, saidstop is attached to the underneath side of said blocking mean,, therebypermitting closure of said transverse bore with a minimum of shockimpact.